1. Field of the Invention
The invention relates to a microwave supplying apparatus and microwave plasma system, and particularly, the invention relates to a microwave supplying apparatus capable of supplying a large-area and uniform microwave field and relates to a microwave plasma system using the same.
2. Description of the Prior Art
The microwave plasma is an important tool for the thin film deposition, precision finishing, and surface modification. Because of the high density of ions and high degree of dissociation, the microwave plasma has great activity, reproducibility, and low reaction temperature, and it could be used for PECVD and plasma etching processes in low temperature. Therefore, the microwave plasma is meaningful for the development of large scale integrated circuit, microelectronic device, photoelectric and communication IC, polymer materials, and thin film sensor processes.
Besides, in the electron cyclotron resonance (ECR) microwave plasma, the molecules could be accelerated to gain more energy to result in the density of ion beam, and the processing area of the plasma could be broadened. In other words, the development of the microwave plasma improves the application of ion source.
The usual microwave-plasma apparatus includes a magnetron to generate microwave, and then the microwave is transmitted by the waveguide in specific mode of oscillation through the quartz glass or the dielectric windows to the plasma chamber, so as to ionize the gas by the electric field to produce the plasma.
Recently, to obtain large volume and area plasma, many kinds of microwave plasma source have been developed. These microwave plasma techniques play an important role on the surface modification of large-area semiconductor, photoelectric materials, and polymer materials. The way of producing large-area and uniform plasma is a major issue in the relative field. If the electromagnetic wave could distribute uniform in space, the particles could easily distribute uniform and the plasma could be easily produced.
However, because of the short wavelength of microwave, it is difficult to form a large-area and uniform electromagnetic wave construction. Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a microwave field appearance 100 in the prior art. As shown in FIG. 1, the microwave field appearance 100 in the prior art is focus at two focal points. Though the plasma diffusion effect exists, the plasma produced by the microwave with the microwave field appearance 100 has a uniform problem.
The area of the chamber corresponding to the single micro generator is limited. In the prior art, for uniformly distributing the microwave power to a larger area of the reactive region, a microwave dividing device is configured in a microwave source system. Because the conventional microwave field focuses at two points, the microwave dividing device divides the microwave by the way of Y shape (one to two) to transfer the input microwave signal to two similar microwave signals along two directions.
As mentioned above, the microwave field appearance focusing at two points may result in non-uniform ionization of plasma. Besides, the conventional microwave dividing device only provides one-to-two effect in one level, so many levels of microwave dividing devices are needed to satisfy the requirement of the large area of the plasma processes in practice.